Heat transfer from exothermically reacting fluid in vertical unstirred vessels—I. temperature and flow fields

✍ Scribed by J.R. Bourne; F. Brogli; F. Hoch; W. Regenass

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 765 KB
• Volume: 42
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(87)85039-x

✦ Synopsis

Exothermically reacting fluid poses the danger of temperature run-away (thermal explosion) in some circumstances (e.g. interruption of stirring in a reactor and during storage). If the explosion time is longer than that required to establish free convection in a heat-generating fluid, convection greatly modifies the internal temperature distributions relative to those developed when only conduction operates. Experiments on laminar free convection, using flow visualisation and temperature profiles, showed a thermally stratified core moving slowly upwards and a thin thermal boundary layer on the wall of an unstirred vertical cylindrical vessel. An analogy between the temperature distributions in active (exothermitally reacting) and passive (cooling without reaction) systems at equal heat removal rates was established. It offers a basis for safer and cheaper experiments, whereby information from passive tests may be applied to active systems, provided their rates of heat generation are stationary and uniform. Criticality will occur in the upper layers of fluid when free convection operates and a method is given for predicting it.